This invention relates generally to an electrophoresis system and a method for performing microfluidic manipulation. More particularly, this invention relates to a microfluidic chip and a method for introducing sample for electrophoretic separation.
Electrophoresis is widely used analytical techniques in chemical and biological research, such as DNA sequencing, protein analysis and genetic mapping. The term electrophoresis refers to a process in which charged molecules are separated in a given separation medium, such as an electrolyte solution under influence of an electric filed. The charged molecules migrate through the separation medium and separate into distinct bands due to different mobilities within the separation medium.
A variety of electrophoresis apparatus have been commercially available for analysis of a sample. One such type of the electrophoresis apparatus is a capillary electrophoresis apparatus. The capillary electrophoresis can be considered as one of the latest and most rapidly expanding techniques in analytical chemistry. It refers to a family of related analytical techniques that uses electric fields to separate molecules within narrow-bore capillaries (typically 20-100 um internal diameter) or within channels of a microfluidic device.
In a standard microfluidic capillary electrophoresis device, the sample is introduced into a sample reservoir connected to an injection channel. Due to concerns of contamination by carry-over, the sample reservoir can only be used for a single sample. One can have multiple reservoirs, each connected to the injection channel, but due to the small size of most microfluidic devices, you are limited in the number of reservoirs that can fit on a single device. Therefore one is often faced with the tradeoff of either making a more compact (and thus cheaper) device or making a larger device and being able to analyze a greater number of samples per chip.
It is possible to have the injection channel of an electrophoresis directly connected with a capillary or channel where the sample is flowing through. The challenge is the pressure will force some of the sample into the injection channel, pushing back the electrolyte medium that is disposed within. One solution that has been proposed is having a deep mixing channel connected to the injection channel. The deep and narrow mixing channel introduces additional steps (and thus costs) into the fabrication in order to have channels of varying depth on the same device.
Therefore, there is a need for a new and improved system and method for performing microfluidic manipulation and introducing a sample into an electrophoresis device.